Telephone-exchange system.



No. 737,715. PATENTED SEPT. 1, 1903.

- W. M. DAVIS.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED DEC. 2, 1901- NO MODEL.

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No. 737,715. fatented September 1, 1905.

UNITED STATES PATENT OFFICE.

WILLIAM M. DAVIS, OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGN- MENTS, TO STROMBERG-CARLSON TELEPHONE MANUFACTURING COM- PANY, OF ROCHESTER, NEW YORK, A CORPORATION OF NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

SPECIFICATION forming part of Letters Patent No. 737,715, dated September 1, 1903.

Application filed December 2, 1901- Serial No. 84,377- KNO model-l To all whom it may concern: ments. This function is preferably accom- Be it known that 1, WILLIAM M. DAVIS, a plished by including the supplemental armacitizen of the United States, residing at Ohiture in circuit with the annunciator coil and cago, in the county of Cook and State of Illibattery and a contact which is engaged by 5 nois, have invented a certain new and useful the armature upon the passage of the mag- Improvement in Telephone-Exchange Sysneto signaling-current. When the suppletems, of which the following is a full, clear, mental armature responds to the signalingconcise, and exact description, reference becurrent, circuit is closed through the helix of ing had to the accompanying drawings, formthe annunciator, which circuit includes a to ing a part of this specification. battery of sufficient strength to properly op- Myinvention relates to telephone-exchange erate the main armature and retain it in its systems, and has for its object the provision operated position until the annunciator is of improved signaling apparatus therefor by restored. In order that the annunciator may which two main results are accomplished. be restored, this circuit, which is preferably 15 I am enabled to secure by means of my ina subsidiary circuit, also includes an opervention an effective automatic restoration of ators switching appliance, so that the operthe indicators. ator may open the circuit, and thereby re- Another and very important object gained store the annunciator. This operators switch by the invention is the provision of means ing appliance when employed in connection 20 whereby the annunciators or indicators that with a line-indicator preferably forms a part may ordinarily be ineffective in response to of the line-jack, the subsidiary circuit inthe signaling-current may be made very efeluding continuity contacts that are separated fective by the provision of supplemental acupon the insertion of a plug, therebyautotuating means. This latter feature of my inmatically effecting the restoration of the line- 25 vention is of particular service, for example, signal.

in connection with telephone-exchange sys- My invention is also adapted for use in the tems wherein magneto-electric generators are operation of clearing-out indicators. For this employed at thesubscribersstationsfortranspurpose I prefer to provide the clearing-outmitting signaling -cnrrent over telephoneannunciator magnet with two coils, though I 50 lines in initiating calls and in operating the do not wish to be limited to this arrangeclearing-out indicators, where either by reameut. One of the coils is included in circuit son of the great length of the telephone-lines with the connected telephone-lines, preferor where the resistance is otherwise great ably by being bridged across the same, while the current emanating from the generators is the second coil is included in circuit with a 35 reduced to such an extent that it will be unbattery and an operators switch. This cirable to operate the annunciators. This obcuit, being thus a subsidiary circuit, also injection'has particularly been found where cludes a supplemental armature and a conannunciators employing armatures, annuntact, so that when the ringing-current travciator-levers, and targets are used, which eleerses the winding-in circuit with the tele- 0 ments frequently present such a load to the phone-lines this supplemental armature is electromagnet of the annunciator as to prebrought into engagement with its contact, vent the weak currents emanating from the thereby effecting an energization of the core magneto-generators from operating the indiof the clearing-out magnet, which as a concators. I supplement the main signal inechsequence causes an attraction of the main aranism of each annunciator by an armature mature, thereby causing the presentation and that is preferably delicately pivoted, so as to maintenance of the clearing-out signal until be responsive to very small currents, which the said operators switch is actuated. This armature in turn is adapted to effect the opswitch is preferably in the form of a plugeraliou of the main signal-presenting eleseat switch which is so arranged that the senting device.

.seat, so that the subsidiary circuit of the clearing-out indicator is placed in condition to be operated upon the passage of clearing- V out signaling-current.

After the clearingout signal has been presented the plug is placed within its seat, thereby forcing a sepa-' ration of the contacts that are included in circuit with the subsidiary circuit, thus causing an automatic restoration of the clearingout signal.

I will explain my invention more fully by reference to the accompanying drawings, in which- Figure 1 is a side elevation of an annunciator constructed in accordance with the invention. Fig. 2 is a longitudinal sectional elevation of the structure illustrated in Fig. 1. Fig. 3 is a top view of the rear portion of said structure. Fig. 4 is a rear view of the structure. Fig. 5 is a rear view of the structure with the armatures removed, and Fig. 6 is a diagrammatic view of a telephone-ex change system illustrating the application of the invention.

Like parts are indicated by similar characters of reference throughout the different figures.

Figs. 1 to 5, inclusive, illustrate a construction of a nnunciator that is adapted for use both for line and clearing-out signals. The annunciator there illustrated is provided with a core 1, that is wound with one or two helices of wire, according to the employment of the device as a line or clearing-out annunciator, and which has a main armature 3, that carries a target 4 or other suitable signal-pre- This armature 3, owing to the load imposed thereon by the target 4 and the indicator-arm 5, that unites said target with the armature, may not/respond to all signaling-currents passing over the line, and I therefore supplement this armature by a second armature 6, that is delicately pivoted,

so as to be nicely balanced to readily respond.

to a weak magnetization of the core 1. This armature 6 is included in circuit with the battery and the winding or a winding of the annunciator, this circuit being normally open when the supplemental armature 6 is un'at-. tracted and closed when attracted, the armature carrying for this pu rpose a contact-screw 7 in electrical connection therewith and adapted for engagement with a terminal contact 8 when said armature is attracted. An adjusting-weight 9, carried by the armature 13, is provided for holding the said armature out of electrical connection with the contact 8 when said armature is unattracted. As indicated in Fig. 5, I prefer to employ two pairs of trunnions 10 and 11, between, which the armatures 3 and 6 are supported by means of trunnion-screws constituting pivots for the armatures.

The telephone-exchange system illustrated in Fig. 6 to show the application of the in vention employs well-known substation apparatus at the substations 90 and 120, at each of which stations there are provided a switchhook 12, a'transmitter 13, a local battery 14, the primary of an induction-coil, the secondary 16 of said induction-coil, a receiver 17, a magneto-generator 18, and a magnetobell or other suitable signal-receiver 19. The switch-hook, as is well known, serves when depressed by the receiver to cut in the signaling branch, including the magneto-generator and the signal-receiver, and to open the conductors, including the transmitter and receiver. The substations are connected with the exchange in this instance by metallic circuits whose sides 20 and 21 are connected with the line-springs of the spring-jacks 22. Cord connecting apparatus employing wellknown instrumentalities for connecting subscribers for conversation is illustrated, there being shown a connecting-plug 23 and an answering-plug 24, united by the tip and sleeve strands, a calling-generator 25, an operators telephone set 26, and a switch 27, serving to include either the calling-generator or the operators telephone appliance in circuit. Each telephone-line is provided with a lineindicator 28, that preferably has the features of mechanical construction illustrated in Figs. 1 to 5, inclusive, parts of the annunciators 28, that are similar to parts shown in Figs. 1 to 5, inclusive, having similar characters of reference. The supplemental armatures 6 and their contacts 8 are adapted for inclusion in circuit with a battery 29, there being also included in circuit with each supplemental armature and its contact the longer line-spring of the corresponding spring-jack and the back contact of the said line-spring.

In initiating a call the calling subscriber operates his generator 18; but supposing that the current emanating from this generator is insufficient to actuate the line-indicator it will prove suificient to operate the delicately-adjusted armature 6, which thereupon engages ,its contact 8 to close a'circuit that includes the battery 29, the winding of the line indicator or annunciator, the supplemental armature with its contact, and the long linespring of the spring-jack with its back contact. The current from battery 29 is strong enou'ghgto energize the magnet of the actuated line-indicator sufficiently to present a line-signal. Theoperator in response to the call insertsan answering-plugas, for example, the plug 24, assuming subscriber 120 to be the calling subscriberwhich separates the contact 30 from its long line-spring, thereby opening the circuit, including the line-in-. dicator magnet, the battery 29, and the supplemental armature, thereby automatically restoring the line-signal. Having ascertained the called subscriber, the operator completes I the connection by inserting-the cord connecting-plug within the jack of the called subscriber. The cord-circuit is provided with an improved form of clearing-out annunciator, which also preferably possesses the same general mechanical characteristics of the structure illustrated in Figs. 1 to'5, inclusive. This clearing-out annunciator or indicator, however, is preferably provided with a magnet that has two helices. The main helix 31 is preferably included in bridge between the strands of the cord-circuit, while the supplemental helix 32 is included in circuit with the supplemental armature 6, the contact 8' for the said supplemental armature, the battery 29, and the plug-seat switch 33, whose contacts are engaged when the plug 24 is re moved from its seat. When the subscribers are through conversation, signaling-current from a magneto'generator is passed over the line through the helix 31, which current, however, may be strong enough to operate only the supplemental armature 6 without effect ing an actuation of the main armature 3. WVhen the supplemental armature 6 is operated, however, it engages its contact 8, thereby including the battery 29 in closed circuit with the supplemental helix 32, whereupon the clearing-out signal is manifested to the operator. The operator thereupon restores the plugs 23 and 24 to their seats, the plug 24 effecting a separation of the contacts forming the plug-seat switch 33, thereby opening the circuit including the supplemental helix 32 and efiecting an automatic restoration of the clearing-out annunciator.

While I have herein shown and particularly described the preferred embodiment of my invention, it is obvious that changes may readily be made without departing from the spirit thereof, and I do not, therefore, wish to be limited to the precise construction herein set forth; but,

Having described my invention, I claim as new and desire to secure by Letters Patent- I. In a telephone-exchange system, the combination with the subscribers line extending from a telephone-substation to an exchange, of a line-indicating magnet at the exchange in circuit with the telephone-line, a second armature in addition to the main armature of the said magnet, a subsidiary circuit for the magnet controlled by the second armature and closed thereby upon the passage of signaling-current over the telephoneline, and an operators restoring-switch included in and governing the subsidiary circuit, substantially as described.

2. In a telephone-exchange system ,the combination with the subscribers line extending from a telephone-substation to an exchange and terminating at the exchange in a line-jack switch, of a line-indicating magnet at the exchange in circuit with the telephoneline, a second armature in addition to the main armature of the said magnet, a subsidiary circuitrfor the magnet controlled by the second armature and closed thereby upon the passage of signaling-current over the telephone-line, and jack-switch contacts included in said subsidiary circuit at the line-jack switch adapted to be operated by insertion of a plug to effect the restoration of the magnet, substantially as described.

3. In a telephone-exchange system, the combination with the subscribers line extending from a telephone -substation to an exchange, of a line-indicating magnet at the exchange in circuit with the telephone-line,a sec: ,ond armaturein addition to the main armature of the said magnet, a subsidiary circuit for the magnet controlled by the second armature and closed thereby upon the passage of signaling-current over the telephone-line, an operators restoring-switch included in and governing the subsidiary circuit, and a magneto-generator at the substation for directing current through the said magnet to eitect the attraction of the aforesaid second or added armature, substantially as described.

4. In a telephone-exchange system, the combination with the subscribers line extending from a telephone-substation to an exchange and terminating at the exchange in a line-jack switch, of a line-indicating magnet at the exchange in circuit with the telephoneline, a second armature in addition to the main armature of the said magnet, asubsidiary circuit for the magnet controlled by the second armature and closed thereby upon the passage of signaling-current over the telephone-line, jack-switch contacts included in said subsidiary circuit at the line-jack switch adapted to be operated by insertion of a plug to effect the restoration of the magnet; and a magneto-generator at the substation for directing current through the said magnet to efiect the attraction of the aforesaid second or added armature, substantially as described.

5. In a telephone-exchange system, the combination with telephone-lines extending from substations to an exchange, of cord connecting apparatus at the exchange for uniting subscribers for conversation, a clearing-out indicating-magnet at the exchange adapted for inclusion in the cord-circuit, an added armature for said electromagnet, a circuit controlled by the added armature to thereby govern the actuation of the main armature, and an operators restoringswitch for governing the said circuit, substantially as described. i

6. In a telephone-exchange system,the combination with telephone-lines extending from substations to an exchange, of cord connectdescribed. I

7. In a telephone-exchange system, the combination with subscribers lines extending from substations to an exchange, of a cordcircuit at the exchange for uniting subscribers for conversation, a clearing-out magnet provided with a main winding adapted for inclusion in circuit with the telephone-line, a

supplemental winding adapted for inclusion in a subsidiary or independent circuit,an added armature for the clearing-out indicatingmagnet, a circuit controlled by the added armature and including the supplemental winding, and an operators switch for opening the circuit including the supplemental winding to effect the restoration of the clearingout indicating-magnet, substantially as described.

8. Inatelephone-exchangesystem,thecombination with subscribers lines extending from substations to an exchange, of a cordcircuit at the exchange for uniting subscribers for conversation, a clearing-out magnet provided with a main winding adapted for inclusion in circuit with the telephone-line, a supplemental winding adapted for inclusion in asubsidiary or independent circuit, an added armature for the clearing-out indicatingmagnet, a circuit controlled by the added armature and including the supplemental winding, and a plug-seat switch included in the supplemental circuit adapted to be operated by the corresponding plug when seated to open the supplemental circuit and thereby efiect a restoration of the clearing-out indicating-magnet, substantially as described.

9. Inatelephone-exchange system,the combination with telephone-lines extending from substations to an exchange, of cord connecting apparatus at the exchange for uniting subscribers for conversation, a clearing-out indieating-magnet at the exchange adapted for inclusion in the cord-circuit, an added armature for said electromagnet, a circuit controlled by the added armature to thereby govern the actuation of the main armature, an operato'rs restoring-switch for governing the said circuit, and a magneto-generator at each of the substations for transmitting signaling-current through the main winding of the clearing-outindicating-magnet,substantially as described.

10. In a telephone-exchange system, the.

combination with telephone-lines extending from substations to an exchange, of cord connecting apparatus. at the exchange for uniting subscribers for conversation, a clearingout indicating-magnet at the exchange adapted for inclusion in the cord-circuit, an added armature for said electromagnet, a circuit controlled by the added armature to thereby govern the actuation of the main armature, a plugseat switch adapted to be operated by a plug when seated to open the said circuit and thereby efl'ect the restoration of the clearing-out indicating-magnet, and a magnetogenerator at each of the substations for transmitting signaling-current through the main winding of the clearing-out indicating-magnet, substantially as described.

11. In a telephone-exchange system, the combination with subscribers lines extending from substations to an exchange, of a cord-circuit at the exchange for uniting subscribers for conversation, a clearing-out magnet provided with a main winding adapted for inclusion in circuit with the telephone-line, a supplemental winding adapted for inclusion in a subsidiary or independent circuit, an added armature for the clearing-out indicating-magnet, a circuit controlled by the added armature and including the supplemental Winding, an operators switch for opening the circuit including the supplement-a1 winding to effect the restoration of the clearing-out indicating-magnet, and a magneto-generator at each of the substations for transmitting signaling-current through the main winding of the clearing-out indicating-magnet, substantially as described.

12. In a telephone-exchange system, the combination with subscribers lines exten ding from substations to an exchange, of a cord-circuit at the exchange for uniting subscribers for conversation, a clearing-out magnet provided with a main winding adapted for inclusion in circuit with the telephone-line, a supplemental winding adapted for inclusion in a subsidiary or independent circuit, an added armature for the clearing-out indicating-magnet, a circuit controlled by the added armature and including the supplemental winding, 2. plug-seat switch included in the supplemental circuit adapted to be operated by the corresponding plug when seated to open the supplemental circuit and thereby eifect a restoration of the clearing-out indicating-magnet, and a magneto-generator at each of the substations for transmitting signaling-current through the main winding of the clearing-out indicating-magnet, substantially as described.

13. In a telephone-exchange system, the combination with telephone-lines extending from subscribers stations to an exchange, of a cord-circuit at the exchange for uniting subscribers for conversation, an electromagnetic signaling appliance associated with said cordcircuit having two helices, a main armature and an additional armature therefor, one of the said helices being adapted for inclusion in circuit with the telephone-line to attract said additional armature upon passage of current, and a switching appliance controlled by said additional armature for governing a circuit including the second helix whereby the actuation of said main armature is controlled, substantially as described.

14:. In a telephone-exchange system, the combination with telephone-lines extending from subscribers stations to an exchange, of a cord-circuit at the exchange for connecting subscribers for conversation, an electromagnetic signaling device associated with said cord-circuit, a main armature, two helices,

IIO

one of said helices being adapted for inclusion in circuit with the main line, a subsidiary circuit including the second helix, an additional armature actuated upon the passage of current through the first helix, and a switching appliance controlled by the said additional armature for controlling the subsidiary circuit including the second helix whereby to control the actuation of said main armature, substantially as described.

15. In a telephone-exchange system, the combination with telephone-lines extending from subscribers stations to an exchange, of a cord-circuitat the exchange for uniting subscribers for conversation, an electromagnetic signaling appliance associated with said cordcircuit having two helices, a main armature and an additional armature therefor, one of the said helices being adapted for inclusion in circuit with the telephone1ine to attract said additional armature upon passage of current, a switching appliance controlled by said additional armature for governing a circuit including the second helix whereby the actuation of said main armature is controlled, and a switch, operated by a connecting-plug, included in the circuit containing the second helix, substantially as described.

16. In a telephone-exchange system, the combination with telephone-lines extending from subscribers stations to an exchange, of a cord-circuit at the exchange connecting subscribers for conversation, an electromagnetic signaling device associated with said cordcircpit, a main armature, two helices, one of said helices being adapted for inclusion in circuit with the main line, a subsidiary circuitincluding the second helix, an additional armature actuated upon the passage of current through the first helix, a switching appliance controlled by the said additional armature for controlling the subsidiary circuit including the second helix whereby to control the actuation of said main armature, and a switch operated by a connecting-plug included in the circuit containing the second helix, substantially as described.

17. In a telephone system, the combination with telephone -lines extending from subscribers stations to an exchange,of a cordcircuit for connecting the subscribers for conversation ,an electromagnetic signaling applian ce at the exchange provided with two armatures, two circuits for said appliance, one adapted for being included in the telephone-line and adapted to be controlled by the subscribers apparatus, the other being included in a supplemental or subsidiary circuit, and a switch controlled by one of the armatures and included in the said subsidiary circuit to thereby effect the control of the other armature, substantially as described.

In witness whereof Ihereunto subscribe my name this 27th day of November,A. D. 1901.

WILLIAM M. DAVIS.

Witnesses:

MAX W. ZABEL, HARVEY L. HANSON. 

